An effective oral composition can maintain and preserve tooth appearance by removing dental stains and polishing the teeth. It may clean and remove external debris as well, which can aid the prevention of tooth decay and promote gingival health.
Abrasives in oral compositions aid in the removal of the tightly adherent pellicle film to which dental stains affix. Pellicle film usually comprises a thin acellular, glycoprotein-mucoprotein coating, which adheres to the enamel within minutes after teeth are cleaned. The presence of various food pigments lodged within the film accounts for most instances of teeth discoloration. An effective abrasive may remove the pellicle film with minimal abrasive damage to oral tissue, such as the dentin and enamel.
In addition to cleaning, it may be desirable for abrasive systems to provide polishing of tooth surfaces, as polished surfaces may be more resistant to ectopic deposition of undesirable components. Tooth appearance may be improved by imparting a polished character to the teeth, because the surface roughness, that is, its polish, affects light reflectance and scattering, which integrally relate to the teeth's visual appearance. The surface roughness also affects tooth feel. For example, polished teeth have a clean, smooth, and slick feel.
Numerous dentifrice compositions use precipitated silicas (among other materials) as abrasives. Precipitated silicas are noted and described in U.S. Pat. No. 4,340,583, Jul. 20, 1982, to Wason, EP Patent 535,943A1, Apr. 7, 1993, to McKeown et al., PCT Application WO 92/02454, Feb. 20, 1992 to McKeown et al., U.S. Pat. No. 5,603,920, Feb. 18, 1997, and U.S. Pat. No. 5,716,601, Feb. 10, 1998, both to Rice, and U.S. Pat. No. 6,740,311, May 25, 2004 to White et al.
While generally providing safe and effective cleaning of teeth, precipitated silicas in oral compositions may present compatibility problems and undesirable interactions with other desirable formula actives, such as metal ions, peroxide, fluoride and cationic antibacterials. These undesirable interactions may lead to reduction in the amount of active available in the formulation and/or reduction in product efficacy. These compatibility problems have been shown to be directly related to surface properties of precipitated silicas such as surface area, number of hydroxyl groups, and porosity. Another potential problem linked with surface properties of precipitated silicas used in oral composition is interactions with flavor components in the formula. This interaction may lead to production of off-flavors over the shelf life of the product, rendering the product unacceptable to consumers.
A need therefore exists for an abrasive system that first and foremost provides effective and safe cleaning and polishing of teeth and further has good compatibility with oral care actives such as key dentifrice components in oral compositions, particularly oral care compositions. In addition, there exists a continuing need for abrasives that can produce superior cleaning and polishing at reduced costs.
Commercially available polyorganosilsequioxane particles, more specifically polymethylsilsesquioxane silicone resin particles are commonly used in cosmetic applications to provide water repellency, lubricity, and impart a smooth, silky feel and/or appearance to skin. Materials sold by Momentive, under the tradename “TOSPEARL” are examples of such silicone resins, also known as T-resins or methylsilsesquioxanes. TOSPEARL 120A, 130A, 145A, 150KA and 2000B resins are commercially available spherical silicone resins available in 2.0, 3.0, 4.5, 5.0 and 6.0 micron median particle sizes, respectively.